Fix char2wchar/wchar2char to support collations properly.

These functions should take a pg_locale_t, not a collation OID, and should
call mbstowcs_l/wcstombs_l where available.  Where those functions are not
available, temporarily select the correct locale with uselocale().

This change removes the bogus assumption that all locales selectable in
a given database have the same wide-character conversion method; in
particular, the collate.linux.utf8 regression test now passes with
LC_CTYPE=C, so long as the database encoding is UTF8.

I decided to move the char2wchar/wchar2char functions out of mbutils.c and
into pg_locale.c, because they work on wchar_t not pg_wchar_t and thus
don't really belong with the mbutils.c functions.  Keeping them where they
were would have required importing pg_locale_t into pg_wchar.h somehow,
which did not seem like a good plan.

5 files changed, 16 insertions, 7 deletions

diff --git a/src/include/mb/pg_wchar.h b/src/include/mb/pg_wchar.h
index 8efc6d3046..826c7af53b 100644
--- a/src/include/mb/pg_wchar.h
+++ b/src/include/mb/pg_wchar.h
@@ -19,8 +19,6 @@
 #ifndef PG_WCHAR_H
 #define PG_WCHAR_H
 
-#include <sys/types.h>
-
 /*
  * The pg_wchar type
  */
@@ -392,11 +390,6 @@ extern int	pg_mbcharcliplen(const char *mbstr, int len, int imit);
 extern int	pg_encoding_max_length(int encoding);
 extern int	pg_database_encoding_max_length(void);
 
-#ifdef USE_WIDE_UPPER_LOWER
-extern size_t wchar2char(char *to, const wchar_t *from, size_t tolen, Oid collation);
-extern size_t char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen, Oid collation);
-#endif
-
 extern int	PrepareClientEncoding(int encoding);
 extern int	SetClientEncoding(int encoding);
 extern void InitializeClientEncoding(void);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 3ee1d077a5..04560c74bf 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -656,6 +656,9 @@
 /* Define to 1 if you have the `wcstombs' function. */
 #undef HAVE_WCSTOMBS
 
+/* Define to 1 if you have the `wcstombs_l' function. */
+#undef HAVE_WCSTOMBS_L
+
 /* Define to 1 if you have the <wctype.h> header file. */
 #undef HAVE_WCTYPE_H
 
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 177bca1bd5..b85bf411de 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -538,6 +538,9 @@
 /* Define to 1 if you have the `wcstombs' function. */
 #define HAVE_WCSTOMBS 1
 
+/* Define to 1 if you have the `wcstombs_l' function. */
+#define HAVE_WCSTOMBS_L 1
+
 /* Define to 1 if you have the <wctype.h> header file. */
 #define HAVE_WCTYPE_H 1
 
diff --git a/src/include/port/win32.h b/src/include/port/win32.h
index 8a3c33f995..2914a59811 100644
--- a/src/include/port/win32.h
+++ b/src/include/port/win32.h
@@ -304,6 +304,8 @@ typedef int pid_t;
 #define iswspace_l _iswspace_l
 #define strcoll_l _strcoll_l
 #define wcscoll_l _wcscoll_l
+#define wcstombs_l _wcstombs_l
+#define mbstowcs_l _mbstowcs_l
 
 
 /* In backend/port/win32/signal.c */
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 25b9d50915..c59a004fc9 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -72,4 +72,12 @@ typedef int pg_locale_t;
 
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
+/* These functions convert from/to libc's wchar_t, *not* pg_wchar_t */
+#ifdef USE_WIDE_UPPER_LOWER
+extern size_t wchar2char(char *to, const wchar_t *from, size_t tolen,
+		   pg_locale_t locale);
+extern size_t char2wchar(wchar_t *to, size_t tolen,
+		   const char *from, size_t fromlen, pg_locale_t locale);
+#endif
+
 #endif   /* _PG_LOCALE_ */